Every few months, the Solar Impulse aircraft embarks upon another test flight, working gradually toward the goal of circumnavigating the globe. Yesterday, it flew for 26 hours, powered through the night by sun it collected during the day.

The flight, according to the Solar Impulse team, was both the longest and the highest ever for a solar-powered aircraft, reaching 28,000 feet above sea level and lasting 26 hours and 9 minutes.

André Borschberg, a former pilot for the Swiss air force, flew the plane, and despite a sore back and the cockpit's overnight temperature of minus 20 degrees Celsius (a temperature that froze his water system and, perhaps even worse, his iPod battery), he understood the significance of his flight:

I've been a pilot for 40 years now, but this flight has been the most incredible one of my flying career... Just sitting there and watching the battery charge level rise and rise thanks to the sun. I have just flown more than 26 hours without using a drop of fuel and without causing any pollution.

The next test for Solar Impulse? A flight across the Atlantic. In the meantime, the team will be starting work on a newer model of the plane that they hope will fly around the world, powered only from the sun, by 2013. [NYT and Business Week]